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arXiv · 1908.08571

Nonequilibrium Orbital Transitions via Applied Electrical Current in Calcium Ruthenate

Hengdi Zhao·Bing Hu·Feng Ye·Christina Hoffmann·Itamar Kimchi·Gang Cao
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Abstract

Simultaneous control of structural and physical properties via applied electrical current poses a key, new research topic and technological significance. Studying the spin-orbit-coupled antiferromagnet Ca2RuO4, with 3% Mn doping to weaken the violent first-order transition at 357 K for more robust measurements, we find that a small applied electrical current couples to the lattice by significantly reducing its orthorhombicity and octahedral rotations, concurrently diminishing the 125 K- antiferromagnetic transition and inducing a new, orbital order below 80 K. Our effort to establish a phase diagram reveals a critical regime near a current density of 0.15 A/cm2 that separates the vanishing antiferromagnetic order and the new orbital order. Further increasing current density (> 1 A/cm2) enhances competitions between relevant interactions in a metastable manner, leading to a peculiar glassy behavior above 80 K. The coupling between the lattice and nonequilibrium driven current is interpreted theoretically in terms of t2g orbital occupancies. The current-controlled lattice is the driving force of the observed novel phenomena.

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Hengdi Zhao, Bing Hu, Feng Ye, Christina Hoffmann, Itamar Kimchi, Gang Cao. 2019-11-18. Nonequilibrium Orbital Transitions via Applied Electrical Current in Calcium Ruthenate. https://doi.org/10.1103/physrevb.100.241104

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